To determine if elevator brakes are operating properly, it is known to use hardware elements such as microswitches and proximity sensors on the elevator brake to directly monitor the mechanical movement and/or position of the brake shoes or pads. Frequently, these sensors are less reliable than the brake itself and therefore cause false indications of brake discrepancy, resulting in unnecessary shutdown of the elevator. Thus, in addition to the initial cost of the switches and/or sensors, there is the additional cost associated with service calls and replacement of the switches and sensors.
Heretofore, the only check on the torque capability of the elevator brake has been provided by inferring the brake condition from the switches and sensors that determine the degree of motion and position of the brake, when it is in the engaged position. However, only the most flagrant malfunctions are detectable in this way. Other malfunctions such as aging of roller guides, can cause undesired drag on the elevator, and the detection of such is advantageous.